1. Field of the Invention
The invention relates to the synthesis of boroxarophenanthrenes. Specifically, it relates to the preparation of 10-hydroxy-10,9-boroxarophenanthrene by reaction of BCl.sub.3 with o-phenylphenol in a liquid hydrocarbon slurry at from about 0.degree. to about 80.degree. C. room temperature.
The product is useful as an antioxidant (see U.S. Pat. Nos. 3,287,270 or 3,320,165) or as an antifatigue agent for lubricants.
2. Discussion of the Prior Art
It is well known that lubricating oil fractions are subject to deterioration from fatigue and oxidation under conditions of use such as in modern internal combustion engines. Oxidation products are formed in the oil which products are acidic in nature and exert an oxidative effect on metal parts with which the oil comes in contact. Furthermore, these oxidation products produce formations of varnish and sludge on the engine surfaces. This tends to lower the operating efficiency of the engine. The proper lubrication of engine parts is further hampered due to the detrimental effect of oxidation on the viscosity of the oil. Similarly, it is known that the oxidation of fuels, particularly during storage, causes gum formation and layer deposits which tend to cause operating malfunctions.
In order to overcome, insofar as possible, these undesirable effects, additives known as antioxidants are normally added to the lubricants and fuels. For example, phenolic or amine compounds are commonly employed as such additives. Modern technology, however, requires lubricants and fuels possessing increased resistance to oxidation.
It has been found that certain 10,9-boroxarophenanthrenes are effective in improving the oxidation and fatigue properties of lubricants. However, the presently known method of making them is time consuming and expensive. The known method is exemplified in U.S. Pat. No. 3,287,270.
Another reference of interest to this invention is U.S. Pat. No. 3,437,596 which, like U.S. Pat. No. 3,287,270, discloses the addition of a phenylphenol to a mixture of BCl.sub.3 and methylene while maintaining the mixture at from -50.degree. C. to -70.degree. C.